I got a Roomba too. Kyuubi will intentionally lie down near it. It almost seems like he's taunting the Roomba to try and run him over. Then when the Roomba approaches, he'll start pawing at it while still lying down until the Roomba changes direction.

Azrael will attack it from behind. He'll stalk it and give it a couple of good smacks. However, sometimes the Roomba will change direction (do a 180) and move right at him... which causes Azrael to run away.

BTW, I got all hardwood floors and two cats who like to splash around in the kitty litter. The Roomba does an excellent job at cleaning up all the litter. Plus I just let it run while I'm at work... which gives my cats about an hour of entertainment when I'm not there.